Magnetic resonance tomography, also known as nuclear spin tomography, has become a wide spread technique for acquiring images of the insides of a living examination object. To obtain an image using this method, i.e. a magnetic resonance recording of an examination object, the body and/or the body part of the patient to be examined must initially be exposed to as homogeneous and static a base magnetic field as possible (generally referred to as B0-field), which is generated by a base field magnet of the magnetic resonance system. During the recording of the magnetic resonance images, rapidly switching gradient fields for spatial encoding are superimposed onto this basic magnetic field, said gradient fields being generated by so-called gradient coils. Furthermore, HF signals, for instance a high frequency pulse or a high frequency pulse sequence, of a defined field strength are irradiated into the examination volume using a high frequency antenna, in which examination volume the examination object is located. This HF field (generally referred to as B1 field) excites the nuclear spin of the atoms in the examination object such that they are moved from their equilibrium position, which runs parallel to the base magnetic field, and rotate about the direction of the base magnetic field. The magnetic resonance signals generated as a result are received by high frequency receiver antennae. The receiver antennae can either be the same antennae with which the high frequency pulses are emitted, or can be separate receiver antennae. The magnetic resonance images of the examination object are finally created on the basis of the received magnetic resonance signals. Each pixel in the magnetic resonance image is assigned here to a small body volume, a so=called “voxel”, and each brightness or intensity value of the pixels is linked to the signal amplitude of the magnetic resonance signal received from this voxel.
A magnetic resonance system, which forms part of a combined imaging system according to the invention, is known for instance from the patent application DE 10 2007 057 495 A1.
A medical imaging method known as a “UWB radar” (ultra wideband radar) is also known, with which images of a living examination object can likewise be obtained. Here the examination object is irradiated with wideband electromagnetic low-power pulses, which penetrate into the examination object and are partially reflected onto boundary layers of tissue types with different dielectric properties. The UWB signal is herewith generated by a UWB signal generator and is radiated into the examination room by way of an antenna. A receiver antenna in conjunction with a receiving facility thereupon receives a UWB echo signal from different depths of the examination object. A display of these biological processes is possible by means of a movement of the boundary layers between the tissue types, which is caused by breathing or the heartbeat.
U.S. Pat. No. 5,668,555 discloses a UWB radar for examining an examination object, in which a pulse sequence is sent out to the examination object and the signals reflected thereupon by the examination object are received and evaluated. It is also possible on the basis of this measuring principle to generate image data from the examination object.
A combination of the two cited methods which form a combined imaging system is known from the publication F. Thiel, M. A. Hein, J. Sachs, U. Schwarz, F. Seifert: “Physiological signatures monitored by ultra-wideband-radar validated by magnetic resonance imaging”, Proc. WEE ICUWB 2008, vol. 1, pp 105-108.
The combination of the two imaging methods enables examinations to be carried out in real-time on living examination objects and the heartbeat or the breathing to be displayed for instance.
A combined imaging system comprising a magnetic resonance system and a UWB radar is disadvantageous in that the signals generated by the respective system can effect interferences in the received signal of the respective other signal.